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I have a new FELT Cyclocross frame and i am looking for a BB30 Crank to go with it. I don't really need more more than one chainring, so i end up looking at a lo9t of MTB cranks on eBay.

What are the CONS of putting a MTB crank on my Cyclocross Bike? Any known Problems?

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A small difference is that MTB cranks attach the chainrings with 4 bolts, while road use 5 (Shimano). So chainrings are not compatible. –  Vorac Mar 14 at 9:34
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Vorac, that's a good point but not really an issue here since it sounds like Andresch is planning on replacing the entire crankset, not just a chainring. –  Gary.Ray Mar 14 at 12:45
    
@Gary.Ray right. that is no problem here :D –  Andresch Serj Mar 14 at 12:51

2 Answers 2

up vote 2 down vote accepted

The only possible drawback[1] to using an MTB crank is that they tend to have a wider stance or Q-factor as it's called.

More on Q-factor http://www.slowtwitch.com/Tech/Stance_Width_2562.html

They are also designed to work with a chainline on a 135mm hub vs 130mm road, but that is lost in the noise and doesn't really matter if you are running a single chainring.

I use an MTB crank on my cross bike and it works just fine.

[1]- Other than the obvious one of available chainring sizes.

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There may be something that I don't know about, but if the crank fits on the bottom bracket, and if the chainring is reasonably close to the position of a middle ring on a triple chainring setup, then your chain line should be fine and everything should work. A lot of bike targeted at young riders have a single front ring and 7 or 8 gears in the back.

The chain line is the most important thing to consider, since you don't want excessive torque on the chain when you are in either the lowest or highest gear.

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Keep in mind that you'll need some sort of chain retention to run a 1x setup with a single chainring. Otherwise you're likely to drop a chain easily. This can be done with bash guard / jump stop or something like a wolf tooth components narrow-wide chainring (similar to the tech used in the sram XX1 mountain drivetrains). –  Benzo Mar 13 at 14:00
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You don't necessarily need a chain guide, just a chainring designed to be used singularly, with full-height teeth. –  Emyr Mar 14 at 9:11

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